Carton manufacturers often face the challenge of providing a carton with handles that are sufficiently strong to support the weight of a group of articles while minimizing material costs. In many instances, the desired thickness of the material that is used to form the carton has a burst strength that is insufficient to avoid failure of the handle under the stress caused by the weight of the articles.
One approach to resolving this quandary is to construct the carton from a stronger material such as corrugated board or from a sheet of material of a relatively higher caliper. As fully enclosed cartons typically have six walls (top, sides, bottom, and ends) that are formed from a single sheet of material, and cost tends to increase according to the strength and thickness of material used to construct the carton walls, this approach is an expensive one because it effectively amounts to reinforcing all of the walls of the carton irrespective of the relative magnitude of the forces borne by each wall.
According to another approach, additional material is applied to or around the handle opening as needed to reinforce the handle as well as the portion of the wall surrounding the handle opening. For instance, a handle opening in a carton end wall may be reinforced by outlining its edges with an additional layer of sheet material. However, it is advantageous from a manufacturing point of view to form a carton from a single sheet of material rather than to attach additional components to a carton or carton blank.
Cartons are sometimes formed from a blank that includes side end flaps and top end flaps that at least partially define an end closure. The top end flap includes a handle opening and the side end flaps include cutouts such that the side end flaps reinforce the handle opening, as known in the art. In addition, another layer of reinforcement is provided by side flap reinforcing panels which are hingedly connected to the side end flaps. Specifically, the side flap reinforcing panels are foldable to overlap at least a portion of the side end flaps adjacent to the cutouts. However, such a blank requires special folding and gluing steps and is thereby more difficult and costly to manufacture.
What is needed is a carton that is formed from a single blank, provides a reinforced handle opening, is efficiently constructed without wasting expensive material to reinforce portions of the carton that are less likely to fail, and is easily erected.